Ejector with cooled walls



July 1, 19240 A. DELAS EJECTOR WITH COOLED WALLS Original Filed Sept. 18, 1919 I Inver or wqfiw/ By AttorneyJ Patented July 1, 1924.

1 UNITED STATES PATENT OFFICE.

ALBERT DELAS, OF PARIS, FRANCE, ASSIGNOR TO DELAS CONDENSER CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

EJ'EOTOR WITH COOLED WALLS.

Application filed September 18, 1919, Serial No. 324,391. Renewed November 17, 1928.

T 0 all whom it may concern:

Be it known that I, ALBERT DELAS, a citizen of France, residing at 18 Rue de Liege, Paris, France, have invented certain. new and useful Improvements in Ejectors with Cooled \Valls, of which the following isa full, clear, and exact description.

In the construction of ejectors of a high ratio of compression it has heretofore been the practice to give the diffuser a convergent-divergent form. This form, however, is only suitable when the normal ratio of compression has been attained, as the starting operation is very diflicult. It is diilicult to start because the density of the fluid in the nozzle chamber is much higher than that which must prevail under normal operation. Consequently, the jet of steam which is employed as the motive fluid, not only spreads out but loses a part of its speed by virtue of this denser atmosphere, and for a predetermined surface the weight of the.fluid that it carries along is considerably increased, due to-the high density of this fluid. Therefore, if the distance from the nozzle to the neck of the diffuser has been calculated and proportioned for the maximum efficiency under normal operation the jet of steam will strike the inside wall of the difluser and the ejector will not start. For the same reason the vacuum will fall down (technically known as upsetting) if, during normal operation, some abnormal quantity of fluid rushes in. In order to avoid these difliculties the various builders, up to the present time, have been obliged to construct the neck of the diiIuser for the maximum weight of the fluid to be extracted, and not for normal operation. Also the diffuser in general has been constructed more open than would otherwise be required, in order that the steam, which spreads out at starting, should not touch its inner wall.

The apparatuses just described have an important bearing on the normal operation because, if the neck of the difluser is too large for normal operation, the fluid column forced into the difluser will have a contracted section which is smaller than the neck of the difiuser and will therefore not fit the sides of the diiiuser; and from the moment that the fluid column leaves said sides eddies will be formed which interfere with the output and with the stability of the ejector. To overcome this builders have been obliged to admit extraneous air or other fluid into the difluser in order that the latter may always be filled, thereby preventing the column from expanding and thus giving rise to eddies. The loss of emciency due to the work necessary to compress this air or other fluid admitted is considerable but necessary to stabilize the apparatus. But it is obvious that the maximum of efliciency with such an apparatus is obtained only at the moment of starting and for the poor vacuum. After having used it exclusively certain builders have given up this process of stabilization as too costly and sacrifice both the efliciency and the stability by employing some intermediary method.

Furthermore, in order to allow the starting in certain types of apparatus, it has been necessary to use several nozzles, instead of one, and to reduce the total surface according to the laws governing the quantities of movement under normal operation. This again sacrifices the efliciency, and the use of several nozzles necessitates an extreme reduction in thedimensions of the neck of the nozzlesfew tenths of a millimeter. These nozzles introduce another undesirable characteristic; that is, they are frequently obstructed because of some unfil Eerel deposits carried along by the motive It may therefore be briefly stated that, among others, attempts to stabilize ejectors, the ratio of compression of which are necessarily subject to fluctuations, have been made either by providing air inlets at the throat of the diffuser or in the space in which the vacuum is maintained, or by varying the cross-sectional area of the throat oi thedifluser, either automatically or otherwise in accordance with the ratio of compression, and by varying the amount of motive fluid admitted.

In my copending applications Serial No. 260,6001}, filed October 31, 1918, and Serial No. 260,601%, filed October 31, 1918, I have disclosed means and methods of overcoming the above-described.difiiculties and disadvantages. In these applications I disclose arrangements for cooling the wall of the difi'user of the ejector, thus not only facilitating starting but also increasing the reliability, efficiency and yield. Another and important advantage is that the wall of the diffuser may be made cylindrical insteadof divergent so that the cross-section of the throat is constant in spite of the fact that the latter may, and in fact does, shift up ing the speed of passage or circulation of the cooling fluid; and, third, by making the other receptacle, is admitted through the wall of the diffuser of thin material of good heat-conductivity. Bearing in mind that the only available supply of cooling fluid, under certain conditions, is sea water and that the apparatus should be capable of withstanding the severe stresses incident to the high abnormal temperatures which are reached on failure of the circulation, it

will be realized that the problem of providing a form of ejector, employing the above-mentioned three methods of enhancing the cooling, presents great difficulties. One of the principal objects of the present invention is to provide such an ejector.

VVhileI have illustrated and described herein an ejector of the foregoing construction provided at one of its ends with an intermediate condenser when a plurality of ejectors are employed in series, I make no vclaim herein specifically thereto as that subject matter forms a art of my copending application Serial No. 396,018, filed July 13, 1920.

Referring to the drawings which illustrate what I now consider preferred forms of my invention:

Figure 1 is a sectional elevation illustrating two ejectors in series.

Fig. 2 is a fragmentary sectional elevation illustratingv a modification.

Fig. 3 is a sectional elevation of one form of ejector which is so constructed as to form an intermediate condenser at one end.

Fig. 4 is a fragmentary sectional elevation illustrating a modification of the structure illustrated in Fig 3.

As the two ejectors shown in Fig. 1 are substantially identical, a description of one, or example the upper one, will suffice for both. Steam or other motive fluid is supplied to the nozzle A and enters through the latter into the ejector. The air, gas or vapor or other fluid to be raised in pressure, as for example, Withdrawn from a steam condenser (not shown) or from an passage B which communicates with the space between the expansion nozzle A and the associated annular diffuser C. The latter is preferably constructed of thin copper or other heat-conducting metal and converges at the entrance, thereafter assuming I a cylindrical form. The diffuser is shown shoulder on said casing and a nut D. The

lower end of the diffuser is also secured to said casing M but in order to permit expansion of said diffuser on rise in temperature this connection is made yielding. One form of such a connection is illustrated in Fig. 1 as comprising a flexible washer or annulus E, the periphery of -which is gripped between a shoulder on the casing M and the nut N. The inner edge of the washer E is gripped between the nut P and ring Q, which ring is soldered or otherwise secured to the lowerend of the diffuser C. It will be noted that the nut P is so formed as to slide in the nut N thereby forming a guide. While I am aware that the flexible connection may be provided between the casing M and the diffuser C at the upper end of the latter and that the member E may be made an integral part of the dif fuser, I have selected the above-described arrangement for the purpose of illustration.

In order to facilitate assembly and disassembly of the ejector it is preferable that tion and thereby increase the speed of passage of the cooling fluid the structure illustrated in Fig. 1 may be employed.

A sleeve H surrounds the diffuser, being held at its upper end between the flange on said diffuser and shoulder on the casing M. The lower end of the sleeve is shown centered on the diffuser by means of a plurality of spacers or clips I. The sleeve H is provided at its upper end wlth one or more rows of holes or openings J to permlt passage of the cooling fluid therethrough and conforms substantially throughout its length to the shape of the diffuser. The water or other cooling fluid may be supplied at F and 'leave at G.

It will be seen that by virtue of the abovedescribed construction the cooling fluid is completely isolated from the fluid passing through the diffuser by metallic walls and the diffuser is permitted. Sea Water may y therefore be employed as the cooling fluid without danger of mixing with the fluid passing through the diffuser. Furthermore, although the structure may be readily assembled and taken down, by virtue of the fact Iny-lthis form the elastic or flexible connection shown in Fig. 1 between the diffuser C and casing M is replaced by a sliding connection. The lower end of the diffuser, preferably reinforced by a sleeve R, slides in a gland S suitably secured against rela-v tive movement with respect to the casing M. In this form the cross-section of the annular cooling space between the difluser C and the casing M may be made sufiiciently small to secure the desired speed of passage of the cooling fluid and the sleeve H may be dispensed with.

If a plurality of ejectors are employed in series, as illustrated in Fig. 1, the water or other cooling fluid leaving one ejector at G may be supplied to the next ejector at K, leaving at L.

If it is desired to employ an intermediate condenser between two ejectors in series one may be formed by extending the diffuser C as indicated at'T in Fig. 3. This extension T may be provided with holes U. The upper part of the diffuser shown in Fig. 3 is cooled by circulation water taken before its entry into the condenser, introduced at- F and withdrawn through G. Water may be supplied to the intermediate condenser through the passage V.

In certain cases it may be desirable to employ feeding water which is higher in temperature than the circulating water of the main condenser, for instance, water extracted from the condenser. In other cases the intermediate condenser may be fed by the cooling water of the diffuser. In Fig. 4 the sleeve H is extended at its lower end and the cooling water after having circulated between said sleeve and the diffuser C, penetrates through the holes U. The surplus water leaves through the pipe V which could if necessary or desirable be dispensed with.

The water condensed by the intermediate condenser and which runs off at the lower end of the diffuser C, in the forms shown in Figs. 3 and 4, may be drawn 01? through a tube or pipe at one of the openings U and conveyed to the principal or main condenser. The air which also escapes by the same extremity of the diffuser C may be drawn off by a second ejector connected in series.

In addition to the advantages enumerated above, I wish to polnt out an additional and practically important feature inherent in my invention and not possesed by the prior art devices. When comparatively high degrees of vacuum are desired, it has been proposed to employ a multi-stage ejector system. Such a system may comprise a first stage ejector, which discharges into the suction-inlet of a second stage ejector. I have discovered that if the diffuser of each stage is provided with a substantially cylindrical outlet portion (instead of a diverging outlet) and cooling means are provided for the diffusers, there is a substantially constant relationship between the ratio of compression of the first stage to that of the second stage, even though the total ratio of compression varies. In other words,

ratio of compression of the fiist stage ratio of compression of the second stage where is a constant although the pressure at the intake side ofthe first stage varies over a comparatively wide range.

The importanceof this novel featur will be appreciated if it is borne in mind that any particular two stage system operates most efficiently at a predetermined ratio of ratios of compression. To state this in another' way, such a system will operate with a minimum steam consumption at a certain ratio of ratios of compression. If the ratio of ratios of compression is either increased *or descreased the total steam consumption will rise.

For the sake of emphasis the above described property may be described in still another way. The ratio (R) of the ratios of compression of a two stage system is given by the following equation:

practise. Therefore,

where is is a constant. Transposing,

y Km

where K is a constant and equal to the quotient of k and k. In; other words the inter-stage suction pressure in a two stage system embodying my invention is prop-ortional to the square root of the pressure at the suction side of. the first stage for all variations of thelast mentioned pressiire between th limits permitted in practise in main condensers of steam power plants.

It is to be understood that the invention is not limited to the specific details herein illustrated and described, but can be embodied in other forms without departure from its spirit.

I claim:

1. In an ejector, in combination, a nozzle for the motive fluid, an inlet for the fluid to be exhausted, a diffuser with which said nozzle and .inlet communicate, a casing surrounding said diffuser but spaced therefrom and provided with a cooling fluid inlet and outlet passage, and means for substantially excluding cooling fluid from said diffuser 'but permitting expansion of the latter.

'2. In an ejector, in combination, a nozzle for the motive fluid, an inlet for the fluid to be exhausted, a diffuser into which said nozzle discharges, means forming a jacket around said diffuser, and means comprising an expansion joint connecting said firstnamed means and diffuser.

3. An ejector comprising in combination, a casing, a sleeve within said casing, a diffuser Within said sleeve, and an expansion joint connecting said casing and diffuser.

4. An ejector comprising in combination, a nozzle, an inlet for the fluid to be exhausted, a casing, a diffuser in said casing and into which said nozzle discharges, and a yielding fluid-tight connection between said casing and diffuser.

5. An ejector comprising in combination, a nozzle, an inlet for the fluid to be exhausted, a casing, a diffuser mounted Within said casing and slidably connected thereto adjacent one end of said diffuser, and a fluid-tight connection between said casing and diffuser adjacent the other end of the latter.

6. An ejector comprising in combination, a nozzle, an. inlet for the fluid to'be exhausted, a diffuser, means surrounding said diffuser, a fluid-tight connection between said means and diffuser adjacent one end of the latter, and an elastic fluid-tight connection between said means and diffuser adjacent the other end of the latter.

7. In combination in an ejecting apparatus, an ejector comprising a combined combining and diffuser tube havin an inlet to which fluid to be ejected is dellvered, and a nozzle for delivering motive fluid to said tube, a second ejector arran ed to communicate with the source of flui to be ejected a'nd to dischar e both the fluid ejected and the motive fluid delivered to it to the inlet of the first mentioned ejector, and means for maintaining the ratio of the ratios of compression of said ejectors substantially constant over a considerable variation in the total ratio of compression of said apparatus.v

8. An ejecting system comprising in combination, a plurality of ejectors operating in series, the first of said ejectors including a diffuser, a mixing chamber communicating with the inlet end of said diflusen-and a motive fluid supply nozzle projecting into said mixing chamber; the second ejector of the series comprising a diffuser communicating at its inlet end with the discharge end of the first mentioned diffuser, and a nozzle for delivering motive fluid to the second named diffuser, and means for maintaining the ratio of the ratios of compression of the first stage and second stage ejectors substantially constant over a considerable Variation in the total ratio of compression of the system. i

9. An ejecting system comprising in combination, a plurality of ejectors operating in series, the first of said ejectors including a diffuser having a substantially cylindrical outlet portion, a mixing chamber communieating With the inlet end of said diffuser, and a 'motive fluid supply nozzle projecting into said mixing chamber, the second ejector of the series comprising a diffuser having a substantially cylindrical outlet portion and communicating at its inlet end with the discharge end of the first mentioned diffuser, and a nozzle for delivering motive fluid to the second named diffuser, and means for cooling the outlet portion of each of said diffusers.

10. In combination in an ejecting apparatus, a plurality of steam actuated ejectors connected to operate in series on the fluid to be ejected, and means for maintaining the ratio of the ratios of compression of said ejectors substantially constant over a considerable variation in the total ratio of compression of said apparatus.

11. In" combination in an ejecting apparatus, a plurality of steam actuated ejectors connected to operate in series on the fluid to be ejected and each including a diffuser havinga substantially cylindrical outlet portion, and means for cooling the outlet portion of each of said diffusers.

12. The method of operating two stage steam actuated ejectors which comprises causing the interstage pressure to assume a value proportional to the square root of the instantaneous pressure at the suction side of the first stage on variation of the latter between predetermined limits.

13. The method of raising the pressureof elastic fluid in stages which com rises entraining said fluid with motive uid, converting at least a portion of the velocity of the resulting mixture into pressure in one stage, entraining said elastic fluid with mo- 1 sure in a later stage, and maintaining the ratio of compression of the first stage to that of the second stage substantially constant for a considerable variation in the suction pressure of the first stage.

14. The method of increasing the etiiciency of multi-stage steam-actuated ejectors which consists in maintaining the ratio of the ratio of compression of the first stage to the ratio of compression of the second stage substantially constant over a considerable variation in the suction pressure of the first stage.

15. An ejecting system comprising a plurality of steam actuated ejectors connected to operate in series onthe fluid to be ejected, the first of said ejectors including .a diffuser, a mixing chamber communicating with the inlet end of said diffuser, and a motive fluid supply nozzle projecting into said mixing chamber, the second ejector of the series comprising a diffuser communicating at its inlet end with the discharge end of the first mentioned diffuser, and a nozzle for delivering motive fluid to the second named difluser, in combination with means for cooling each of said diffusers, and means for enabling the cooling fluid from one of said diffusers to be utilized directly for cooling the other diffuser.

16. An ejecting system comprising in combination a plurality of axially aligned ejectors operating in series, the first of said ejectors including a diffuser, a mixing chamber communicating with the inlet end of said difiuser, and a motive fluid supply nozzle projecting into said mixing chamber, the second ejector of the series comprising a diffuser whose inlet end is directly connected with the discharge end of the first mentioned diffuser, and a nozzle for delivering motive fluid to the second named diffuser, and means for maintaining the ratio of the ratios of compression of the first stage and second stage ejectors substantially constant over a considerable variation in the total ratio of compression of the system.

In testimony whereof I hereunto aflix my signature.

ALBERT DELAS. 

